Front seat of a motor vehicle

Abstract

The invention relates to a front seat of a motor vehicle, the seat comprising a backrest (1) that comprises a frame (2), a headrest (4) that comprises an auxiliary frame rotatably mounted at the upper part of the frame about a transverse axis (7), a gear motor (8) for actuating the headrest between a nominal position and a folded position, and a device for locking the headrest in the nominal position, wherein the device comprises a locking means (9) that co-operates with a reciprocal means (10) rigidly attached to the auxiliary frame, and wherein the reciprocal means is offset with respect to the transverse axis so as to improve the retention of the headrest in the nominal position in the event of an impact by an occupant's head moving backward or forward.

Description

[0001] DESCRIPTION

[0002] Title: Front seat of a motor vehicle

[0003] The invention relates to a front seat of a motor vehicle.

[0004] It is known, in particular from document US4807934-A, to produce a front seat of a motor vehicle, said seat comprising:

[0005] • a backrest comprising a frame that can be rotated, so as to allow said backrest to be actuated between a sitting position of an occupant of said seat, where said backrest is substantially vertical, and a lying position of said occupant obtained by folding said backrest backwards, where said backrest is substantially horizontal, said backrest further comprising padding for filling said frame,

[0006] • a headrest comprising an additional frame and a cushion secured to said additional frame, said additional frame comprising two parallel rods, said additional frame being rotatably mounted in the upper part of said backrest frame along a transverse axis offset downwards relative to the top of said padding, so that said headrest can be actuated between a nominal position, where it protrudes from the top of said padding so as to allow support for the head of said occupant, and a position folded backwards,

[0007] • a gear motor for actuating said headrest between said nominal and folded positions.

[0008] Such an arrangement allows for the occupant of the seat to lie down and enjoy a reclining resting position, with motorized operation of the headrest to improve ergonomics.

[0009] However, with such an arrangement, there is a risk of the headrest being held insufficiently robustly in the nominal position in the event of an impact on said headrest by the head of a vehicle occupant. Indeed, in the embodiment of US4807934-A, the locking of the headrest in the nominal use position is ensured solely by the geared motor.

[0010] However, the geared motor may not be sufficiently robust to ensure locking on its own.

[0011] Indeed, the impact of a passenger's head on the headrest can typically correspond - according to observations recorded in an impact situation for a 6.8 kg head projected at 24 km / h - to a dynamic force applied in the order of 550 kg for 3 ms which, by lever arm effect linked to the offset of the point of impact in relation to the axis of rotation of the auxiliary frame, generates a very significant dynamic torque at the level of the geared motor axis.

[0012] As an illustration, for an offset of 250 mm, the dynamic torque is around 140 daN.m, which is considerable.

[0013] And, in practice, it is impossible to have a geared motor usable in a car seat which has a resistance allowing the headrest to be kept in its nominal position in the event of an impact such as that mentioned above.

[0014] The invention aims to overcome this drawback.

[0015] To this end, the invention proposes a front seat of a motor vehicle, said seat comprising:

[0016] • a backrest comprising a frame that can be actuated in rotation, so as to allow actuation of said backrest between a sitting position of an occupant of said seat, where said backrest is substantially vertical, and a lying position of said occupant obtained by folding said backrest backwards, where said backrest is substantially horizontal, said backrest further comprising padding for filling said frame, • a headrest comprising an annex frame and a cushion secured to said annex frame, said annex frame comprising two parallel rods, said annex frame being mounted in rotation in the upper part of said backrest frame along a transverse axis offset downwards relative to the top of said padding, so that said headrest can be actuated between a nominal position, where it protrudes from the top of said padding so as to allow support of the head of said occupant,and a rearward folded position,

[0017] • a geared motor for actuating said headrest between said nominal and folded positions, said seat further comprising a device for locking said headrest in the nominal position, said device comprising a locking means cooperating with a reciprocal means secured to said annex frame, said reciprocal means being offset relative to said transverse axis, so as to reinforce the holding of said headrest in the nominal position in the event of impact by an occupant's head pressed backwards or forwards on said cushion.

[0018] In this description, the terms of positioning in space (top, bottom, longitudinal, transverse, vertical, upper, horizontal, front, rear, etc.) are taken with reference to the vehicle in which the seat back is arranged in the sitting position, said vehicle extending longitudinally along its length (X axis), transversely along its width (Y axis) and vertically along its height (Z axis).

[0019] With the proposed arrangement, the presence of the locking device and its offset relative to the transverse axis makes it possible to reinforce the holding of the headrest in the nominal position in the event of an impact, the geared motor not being sufficiently robust to ensure locking on its own, said offset also making it possible to limit dimensional play and therefore to guarantee overall rigidity.

[0020] Other features and advantages of the invention will appear in the following description, made with reference to the attached figures, in which: [Fig.1] is a schematic representation in transverse view of a seat according to one embodiment, a rear seat part also being shown, said seat presenting its backrest in the extended position and the headrest in the folded position,

[0021] [Fig.2] is a partial schematic perspective view of a front seat according to one embodiment, the headrest of said seat being in the nominal position,

[0022] [Fig.3] is similar to figure 2 from another angle of view, the padding of the backrest not being shown, the headrest being shown in the nominal position (A) and in the position folded backwards (B),

[0023] [Fig.4] is a schematic representation according to a longitudinal view of a device for locking the headrest in the nominal position according to a first embodiment, said device being activated,

[0024] [Fig.5] is a schematic representation according to a longitudinal view of a device for locking the headrest in the nominal position according to a second embodiment, said device being activated.

[0025] With reference to the figures, a front seat of a motor vehicle is described, said seat comprising:

[0026] • a backrest 1 comprising a frame 2 operable in rotation, so as to allow actuation of said backrest between a sitting position of an occupant of said seat, where said backrest is substantially vertical, and a lying position of said occupant obtained by folding said backrest backwards, where said backrest is substantially horizontal, said backrest further comprising padding 3 for filling said frame,

[0027] • a headrest 4 comprising an ancillary frame and a cushion 5 secured to said ancillary frame, said ancillary frame comprising two parallel rods 6, said ancillary frame being rotatably mounted in the upper part of said backrest frame along a transverse axis 7 offset downwards relative to the top of said padding, so that said headrest can be actuated between a nominal position, where it protrudes from the top of said padding so as to allow support of the head of said occupant, and a rearwardly folded position, • a geared motor 8 for actuating said headrest between said nominal and folded positions, said seat further comprising a device for locking said headrest in the nominal position, said device comprising a locking means 9 cooperating with a reciprocal means 10 secured to said ancillary frame,said reciprocal means being offset - upwards according to the embodiment shown - relative to said transverse axis, so as to reinforce the holding of said headrest in the nominal position in the event of impact by an occupant's head pressed backwards or forwards on said cushion.,

[0028] According to the embodiment shown in Figure 4, the locking device comprises an electromagnet 11 - here in the form of a solenoid - interacting with a part 12 - here in the form of a bar inserted into said solenoid - attractable by a magnet, said part being provided with a projection - formed here by one end of said bar - forming the locking means 9, the reciprocal means 10 being formed by a housing, arranged in the annexed frame, for receiving said projection, said device further comprising a spring 14 for returning said part to insert said projection into said housing, said electromagnet being arranged, when it is crossed by a current, so as to move said part against said spring to release said projection from said housing.

[0029] In particular, the locking device comprises two electromagnets 11 each interacting with a respective part 12, each of the rods 6 being provided with a housing 10 for receiving a projection 9 of one of said parts, so as to allow locking on each of said rods.

[0030] According to the alternative embodiment shown in Figure 5, the locking device comprises:

[0031] • a toothed wheel 20 actuated in rotation - in particular by means of a cable 21 according to the embodiment shown - by an additional geared motor not shown,

[0032] • two locking means 9 in the form of latches mounted to slide transversely, said means each being provided with a rack 22 meshing with said wheel and being arranged diametrically on either side of said wheel, so that said means can be actuated between a locking position, where they are inserted into two respective housings, not shown, provided in the annex frame, and an unlocking position where they are released from said housings.

[0033] Such an implementation allows for a greater locking force than that deployed with solenoids, which is useful for countering sliding forces linked to dimensional dispersions that can be observed.

[0034] According to the embodiment shown, the geared motor 8 has a rotation shaft 15 coaxial with the transverse axis 7.

[0035] According to one embodiment, the reciprocal means 10 is offset by at least 40 mm relative to the transverse axis 7, so as to allow optimized force recovery in the event of an impact on the headrest 4.

[0036] According to the embodiment shown, the upper part of the padding 3 is provided with two grooves 16 arranged so as to allow the rods 6 to pass through when the headrest 4 is rotated from one position to another.

[0037] According to the embodiment shown, as illustrated in figure 1, the headrest 4 in the folded position does not protrude from the top of the padding 3, so as to avoid interference with a rear seat 17 of the vehicle when the backrest 1 is put in the extended position.

Claims

CLAIMS 1. Front seat of a motor vehicle, said seat comprising: • a backrest (1) comprising a frame (2) operable in rotation, so as to allow actuation of said backrest between a sitting position of an occupant of said seat, where said backrest is substantially vertical, and a lying position of said occupant obtained by folding said backrest backwards, where said backrest is substantially horizontal, said backrest further comprising padding (3) for filling said frame, • a headrest (4) comprising an additional frame and a cushion (5) secured to said additional frame, said additional frame comprising two parallel rods (6), said additional frame being rotatably mounted in the upper part of said backrest frame along a transverse axis (7) offset downwards relative to the top of said padding, so that said headrest can be actuated between a nominal position, where it protrudes from the top of said padding so as to allow support for the head of said occupant, and a position folded backwards, • a geared motor (8) for actuating said headrest between said nominal and folded positions, said seat being characterized in that it further comprises a device for locking said headrest in the nominal position, said device comprising a locking means (9) cooperating with a reciprocal means (10) integral with said annex frame, said reciprocal means being offset relative to said transverse axis, so as to reinforce the holding of said headrest in the nominal position in the event of impact by an occupant's head pressed backwards or forwards on said cushion.

2. Seat according to claim 1, characterized in that the locking device comprises an electromagnet (11) interacting with a part (12) attractable by a magnet, said part being provided with a projection forming the locking means (9), the reciprocal means (10) being formed by a housing, arranged in the annex frame, for receiving said projection, said device further comprising a spring (14) for returning said part to insert said projection into said housing, said electromagnet being arranged, when it is crossed by a current, so as to move said part against said spring to release said projection from said housing.

3. Seat according to claim 2, characterized in that the locking device comprises two electromagnets (11) each interacting with a respective part (12), each of the rods (6) being provided with a housing (10) for receiving a projection (9) of one of said parts, so as to allow locking on each of said rods.

4. Seat according to claim 1, characterized in that the locking device comprises: • a toothed wheel (20) rotated by an additional geared motor, • two locking means (9) in the form of latches mounted to slide transversely, said means each being provided with a rack (22) meshing with said wheel and being arranged diametrically on either side of said wheel, so that said means can be actuated between a locking position, where they are inserted into two respective housings, not shown, provided in the annex frame, and an unlocking position where they are released from said housings.

5. Seat according to any one of the preceding claims, characterized in that the geared motor (8) has a rotation shaft (15) coaxial with the transverse axis (7).

6. Seat according to any one of the preceding claims, characterized in that the reciprocal means (10) is offset by at least 40 mm relative to the transverse axis (7), so as to allow optimized force recovery in the event of impact on the headrest (4).

7. Seat according to any one of the preceding claims, characterized in that the upper part of the padding (3) is provided with two grooves (16) arranged so as to allow the passage of the rods (6) when rotating the headrest (4) from one position to the other.

8. Seat according to any one of the preceding claims, characterized in that the headrest (4) in the folded position does not protrude from the top of the padding (3), so as to avoid interference with a rear seat (17) of the vehicle when the backrest (1) is placed in the extended position.

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